Fuel Pressure Relief Valve
WARNING: This page is about a different car, the 2020 Ford F-550 Super Duty, 2020 Ford F-450 Super Duty, 2020 Ford F-350 Super Duty, 2020 Ford F-250 Super Duty, and 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The fuel pressure relief valve is a mechanical spring activated valve. If the pressure exceeds the maximum expected pressure for the system the fuel pressure relief valve activates to relieve fuel pressure back to the fuel tank. The fuel pressure relief valve is not expected to activate during normal vehicle operation. The fuel pressure relief valve has a limited number of activations before the part is no longer reliable and may not fully close. The fuel pressure control valve is mounted at the opposite end of the fuel rail as the fuel rail pressure (FRP) sensor.